CN115265986B - Bridge vibration exciter - Google Patents

Bridge vibration exciter Download PDF

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Publication number
CN115265986B
CN115265986B CN202211189537.8A CN202211189537A CN115265986B CN 115265986 B CN115265986 B CN 115265986B CN 202211189537 A CN202211189537 A CN 202211189537A CN 115265986 B CN115265986 B CN 115265986B
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Prior art keywords
rotating shaft
inertial mass
mass block
spring
bridge
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CN115265986A (en
Inventor
汪正兴
柴小鹏
荆国强
王波
肖龙
吴肖波
马长飞
李亚敏
戴青年
贾晓龙
董飞
黄启文
尹康
董京礼
曹冠军
王鼎鑫
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China Railway Major Bridge Engineering Group Co Ltd MBEC
China Railway Bridge Science Research Institute Ltd
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China Railway Major Bridge Engineering Group Co Ltd MBEC
China Railway Bridge Science Research Institute Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M7/00—Vibration-testing of structures; Shock-testing of structures
    • G01M7/02—Vibration-testing by means of a shake table
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/10—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of mechanical energy
    • B06B1/16—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of mechanical energy operating with systems involving rotary unbalanced masses
    • B06B1/161—Adjustable systems, i.e. where amplitude or direction of frequency of vibration can be varied
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H19/00—Gearings comprising essentially only toothed gears or friction members and not capable of conveying indefinitely-continuing rotary motion
    • F16H19/02—Gearings comprising essentially only toothed gears or friction members and not capable of conveying indefinitely-continuing rotary motion for interconverting rotary or oscillating motion and reciprocating motion
    • F16H19/04—Gearings comprising essentially only toothed gears or friction members and not capable of conveying indefinitely-continuing rotary motion for interconverting rotary or oscillating motion and reciprocating motion comprising a rack
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H33/00—Gearings based on repeated accumulation and delivery of energy
    • F16H33/20—Gearings based on repeated accumulation and delivery of energy for interconversion, based essentially on inertia, of rotary motion and reciprocating or oscillating motion

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Vibration Prevention Devices (AREA)

Abstract

The invention relates to a bridge vibration exciter, which is used for testing the damping ratio of a bridge and comprises the following components: the fixed box comprises a top plate, and the top plate is provided with an actuator; the inertia mass block is located in the fixed box, the inertia mass block is connected with the actuator through a first spring, the inertia mass block is connected with the top plate through a second spring, and the second spring is used for bearing the dead weight of the inertia mass block. According to the bridge vibration exciter, under the vibration excitation of the actuator, the inertia mass block can resonate with the actuator, so that the amplitude of the inertia mass block is amplified, and the amplitude of the girder of the bridge is in direct proportion to that of the inertia mass block.

Description

Bridge vibration exciter
Technical Field
The invention relates to bridge excitation equipment, in particular to a bridge vibration exciter.
Background
In recent years, a large wind vibration problem occurs in a plurality of large-span suspension bridges in succession, and the vibration control and the improvement of the dynamic performance of the suspension bridges lack accurate damping ratio parameters as a basis. At present, environmental excitation and sports car excitation are mostly adopted in bridge damping ratio tests, excitation energy is insufficient, and result discreteness is large. For large-span and ultra-large-span bridges, the field steady-state excitation test is the only means for accurately measuring the multi-order modal damping ratio of the large-span bridge, the field steady-state excitation of the large-span bridge is difficult to realize, the technology is owned by only countries such as America, japan and Korean, and the research and development aspect of adopting the large-scale excitation technology in the large-span bridge test of China is still blank. Therefore, independently researching and developing special large-scale bridge excitation equipment has great significance to the field of engineering vibration in China.
In the related technology, at present, when the girder vibration of a large-span bridge is excited, an actuator is arranged at the position of the maximum vibration mode, so that the excitation frequency of the actuator is consistent with the frequency of the intended excitation mode of the girder, and the vibration amplitude of the specific mode of the girder is continuously increased.
However, as the amplitude of the bridge of the excitation method is larger, the stroke of the required actuator is increased, on one hand, the overall structure size is increased due to the increase of the stroke of the actuator, on the other hand, the performance requirements of the actuator are improved, including the influence of the stroke and the speed, the stroke is larger than +/-1 m, the speed is larger than 1m/s, the processing difficulty of the actuator is increased sharply, and the price of the actuator is also increased greatly.
Therefore, there is a need for a new bridge exciter to overcome the above problems.
Disclosure of Invention
The embodiment of the invention provides a bridge vibration exciter, and aims to solve the problem that the larger the amplitude of a bridge is, the larger the stroke of a required actuator is.
In a first aspect, a bridge vibration exciter is provided for testing a damping ratio of a bridge, and comprises: the fixed box comprises a top plate, and the top plate is provided with an actuator; the inertia mass block is located in the fixed box, the inertia mass block is connected with the actuator through a first spring, the inertia mass block is connected with the top plate through a second spring, and the second spring is used for bearing the dead weight of the inertia mass block.
In some embodiments, an inerter is mounted on the side surface of the inertial mass, and the inerter comprises a rotating shaft connected with the inertial mass and a flywheel mounted on the rotating shaft; when the inertia mass block moves along the extension direction of the first spring, the inertia mass block drives the flywheel to rotate around the axis of the rotating shaft.
In some embodiments, the rotating shaft is rotatably connected to the inertial mass through a bearing, and the flywheel is fixedly arranged at one end of the rotating shaft close to the inertial mass; the inertial mass block drives the rotating shaft to move synchronously, and meanwhile, the transmission piece drives the rotating shaft to rotate around the axis of the rotating shaft.
In some embodiments, the transmission comprises: the rack is fixedly arranged on the fixed box; the gear is fixedly arranged on the rotating shaft and meshed with the rack, when the rotating shaft moves along the extending direction of the first spring, the rotating shaft drives the gear to move along the rack, and meanwhile, the gear drives the rotating shaft to rotate.
In some embodiments, the inerter further comprises a limiting assembly, the limiting assembly comprises a connecting rod and a limiting wheel, the connecting rod connects the rotating shaft and the limiting wheel, and the limiting wheel and the gear are located on two opposite sides of the rack.
In some embodiments, opposite sides of the gear are fixed by fastening nuts, and whether the gear is engaged with the rack can be adjusted by tightening or loosening the fastening nuts on the two sides.
In some embodiments, the inerter further comprises a limiting assembly that limits disengagement of the rotating shaft from the transmission member.
In some embodiments, the fixing box further comprises a bottom plate, a lifting column is fixedly arranged on the bottom plate, the top end of the lifting column is connected with the top plate, and the lifting column can adjust the height between the top plate and the bottom plate.
In some embodiments, a plurality of inertance containers are mounted on the side surface of the inertial mass, each inertance container comprises a rotating shaft connected with the inertial mass and a flywheel mounted on the rotating shaft, and the inertance container further comprises a transmission part; when the rotating shaft of the inertial container is connected with the corresponding transmission piece, the inertial mass block can drive the flywheel to rotate around the axis of the rotating shaft; the number of the flywheels participating in rotation can be adjusted by adjusting the connection state of the rotating shaft and the corresponding transmission member.
In some embodiments, the top plate is provided with a through hole, and the actuator comprises a main machine located outside the top plate and a telescopic rod connected with the main machine, wherein the telescopic rod penetrates through the through hole and extends to the inside of the fixed box; the telescopic rod is fixedly provided with a flange plate, and the flange plate is connected with the inertia mass block through a plurality of first springs.
The technical scheme provided by the invention has the beneficial effects that:
the embodiment of the invention provides a bridge vibration exciter, wherein an actuator is connected with an inertia mass block through a first spring, the inertia mass block is connected to a top plate through a second spring, the second spring can bear the dead weight of the inertia mass block, the inertia mass block can resonate with the actuator under the vibration excitation of the actuator, so that the amplitude of the inertia mass block is amplified, and the amplitude of a girder of a bridge is in direct proportion to that of the inertia mass block, so that the bridge vibration exciter can realize that the conventional stroke actuator excites the girder to have large amplitude, and the stroke of the actuator is greatly shortened.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a bridge vibration exciter provided in an embodiment of the present invention, which is mounted on a main beam;
fig. 2 is a schematic perspective view of a bridge vibration exciter according to an embodiment of the present invention;
fig. 3 is a front view schematically illustrating a bridge vibration exciter according to an embodiment of the present invention;
FIG. 4 is a simplified structural schematic diagram of another bridge vibration exciter according to an embodiment of the present invention;
fig. 5 is a front view schematically illustrating another bridge vibration exciter according to an embodiment of the present invention;
fig. 6 is a schematic perspective view of another bridge vibration exciter according to an embodiment of the present invention;
fig. 7 is an enlarged schematic structural view of an inerter according to an embodiment of the present invention.
In the figure:
1. a fixed box; 11. a top plate; 12. a base plate; 13. a lifting column;
2. an actuator; 21. a host; 22. a telescopic rod; 23. flange a plate;
3. an inertial mass block; 4. a first spring; 5. a second spring;
6. an inerter; 61. a rotating shaft; 62. a flywheel; 63. a bearing; 64. a transmission member; 641. a rack; 642. a gear; 65. a limiting component; 651. a connecting rod; 652. a limiting wheel; 66. fastening a nut;
7. a main beam.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The embodiment of the invention provides a bridge vibration exciter, which can solve the problem that the larger the amplitude of a bridge is, the larger the stroke of a required actuator is, the larger the amplitude is in the related art.
According to the structure dynamics principle of forced vibration, when the main beam is excited by simple harmonic load, the dynamic balance equation is as follows:
Figure 760111DEST_PATH_IMAGE001
in the above formula:M、C、Kfor main beam modal mass, stiffness and damping respectively,
Figure 517851DEST_PATH_IMAGE002
respectively the acceleration, the speed and the displacement of the main beam in a simulated excitation mode,P 0 in order to tune the force amplitude for simplicity,mis the inertia mass of the vibration exciter,y 0 the inertia mass of the vibration exciter makes the maximum amplitude of simple harmonic vibration,ωto load the circular frequency for the simple harmonic force, tis time.
Solving the equation to obtain the vibration displacement response of the girder in the simulated excitation mode:
Figure 493897DEST_PATH_IMAGE003
in the above formula:ω n the vibration circle frequency of the main beam in the simulated excitation mode,ξis the modal damping ratio of the mode to be excited.
At this time, the maximum amplitude of the main beam quasi-excitation mode is:
Figure 113229DEST_PATH_IMAGE004
the maximum amplitude of the quasi-excitation mode of the girder and the inertia mass of the vibration exciter are obtainedmAnd main structure modal qualityMRatio of (c), maximum amplitude of simple harmonic vibration of inertial mass of vibration excitery 0 Modal damping ratio of pseudo-excitation modeξIt is relevant.
For the first-stage resonance vibration exciter, the actuator directly excites the mass block, and then the stroke of the actuator is consistent with that of the mass block. When the main beam is excited to a large amplitude, the stroke required by the actuator is large, for example as follows:
it is known that the amplitude of the actuator isy 0 0.5m, 20t of inertial mass, 14000t of modal mass of bridge, damping ratioξIs 0.005. As can be seen from the above formula, when the amplitude a of the lifted main beam is 0.2m, the amplitude of the required actuator is:
Figure 225541DEST_PATH_IMAGE005
at this time, the mass amplitude required to excite the main beam with an amplitude of 0.2m is 1.4m.
When the ultralow frequency is realized by adopting the first-order resonance, the inertia mass of the vibration exciter is in direct proportion to the amplitude of the bridge, the stroke of the required actuator is increased, and the problem of overlarge static deformation of the spring exists. However, the latest technology in japan and korea is the AMD type vibration exciter, and primarily employs the first-order resonance, in which the stroke of the inertial mass is limited by the stroke of the actuator, and on the one hand, the increase of the stroke of the actuator leads to an increase in the overall size of the structure, and on the other hand, the performance requirements for the actuator, including the influence of the stroke and the speed, are increased, the stroke is greater than ± 1m, the speed is greater than 1m/s, the processing difficulty of the actuator is sharply increased, and the price is also increased more. In addition, most of bridge excitation equipment at present has the defects of narrow working frequency range, uncontrollable excitation, complex structure, heavy equipment, high cost and the like, and the invention needs to invent the excitation equipment with two-stage resonance and graded frequency modulation, which drives the mass inertia and large amplitude by a conventional stroke actuator.
Referring to fig. 1 to 3, a bridge exciter according to an embodiment of the present invention is provided for a bridge damping ratio test, and may include: the vibration exciter comprises a fixed box 1, wherein the fixed box 1 comprises a top plate 11, an actuator 2 is installed on the top plate 11, when the vibration exciter is used, the fixed box 1 is fixed on a main beam 7 and vibrates with the main beam 7 at the same frequency, and a cavity can be arranged in the fixed box 1; the inertial mass block 3 can be located in the fixed box 1, the inertial mass block 3 is connected with the actuator 2 through the first spring 4, wherein the inertial mass block 3 can be connected with the actuator 2 through the first spring 4, and also can be connected with the actuator 2 through a plurality of first springs 4, and the inertial mass block 3 can be connected with the top plate 11 through the second spring 5, and the second spring 5 can also be one or more, the second spring 5 is used for bearing the dead weight of the inertial mass block 3. In the present embodiment, the inertial mass 3 is preferably a rectangular parallelepiped. The first spring 4 and the second spring 5 are preferably tension springs, when the number of turns of the first spring 4 or the second spring 5 is reduced, the rigidity of the springs is increased, and the frequency of the vibration exciter can be adjusted upwards.
In this embodiment, the actuator 2 is used as an excitation source, and the first spring 4 is connected to the inertial mass 3 and excites the inertial mass 3 to achieve a resonant state of both the inertial mass 3 and the actuator 2, which is a first-order resonance. And the vibration exciter is fixed on the main beam 7, and when the vibration frequency excited by the inertial mass block 3 is consistent with the frequency of the quasi-excitation mode of the main beam 7, the vibration exciter and the main beam 7 reach a resonance state, and the stage is a second-stage resonance.
In the first-stage resonance, the actuator 2 is connected with the inertia mass block 3 through a spring, the amplitude of the inertia mass block 3 is amplified under the excitation of the actuator 2, and the conventional stroke actuator 2 can excite the inertia mass block 3 to have large amplitude through the amplification effect of the first-stage resonance. The amplitude of the inertial mass 3 = n × the amplitude of the actuator 2 (n is the first-order resonance amplification factor, n > 1), where n is related to the stiffness ratio of the first spring 4 and the second spring 5, and the first-order resonance amplification factor, and thus the amplitude of the inertial mass 3, can be adjusted by adjusting the number of turns of the first spring 4 or the second spring 5, specifically, n is mainly related to the stiffness of the first spring 4, and n increases with the increase of the stiffness of the first spring 4 when the second spring 5 is unchanged. That is, decreasing the effective number of turns of the first spring 4 or increasing the effective number of turns of the second spring 5 can increase n. In the second-stage resonance, the amplitude of the main beam 7 is in direct proportion to that of the inertial mass block 3, so that the large amplitude of the main beam 7 can be excited by the conventional stroke actuator 2 in a two-stage resonance mode, and the stroke of the actuator 2 is greatly shortened compared with that of the first-stage resonance.
In some embodiments, referring to fig. 4 and 5, an inertial mass 3 may be mounted with an inertial container 6 on a side surface thereof, where the inertial container 6 includes a rotating shaft 61 connected to the inertial mass 3 and a flywheel 62 mounted on the rotating shaft 61, where the rotating shaft 61 may be directly connected to the inertial mass 3 or indirectly connected thereto, and the flywheel 62 may be directly mounted on the rotating shaft 61 or indirectly mounted on the rotating shaft 61; when the inertial mass 3 moves along the extending direction of the first spring 4, the inertial mass 3 drives the flywheel 62 to rotate around the axis of the rotating shaft 61. In this embodiment, the actuator 2 is excited in the up-down direction, so that the inertial mass block 3 moves in the up-down direction, wherein other mechanical structures may be connected between the inertial mass block 3 and the rotating shaft 61, so that the up-down motion of the inertial mass block 3 can be converted into the rotating motion of the rotating shaft 61 in the up-down moving process of the inertial mass block 3, and the inertial mass block 3 drives the rotating shaft 61 and the flywheel 62 to rotate around the axis of the rotating shaft 61; of course, the rotating shaft 61 may also be directly mounted on the inertial mass 3 and move up and down along with the inertial mass 3, and meanwhile, the rotating shaft 61 may also be connected with another mechanical structure, so that the rotating shaft 61 can be driven to rotate by the mechanical structure in the process of moving up and down, and thus the inertial mass 3 drives the rotating shaft 61 and the flywheel 62 to rotate around the axis of the rotating shaft 61. In this embodiment, the inertia container 6 is disposed on the side surface of the inertia mass block 3, and when the flywheel 62 mounted on the inertia mass block 3 rotates, the rotation of the flywheel 62 generates rotational inertia, so as to increase the inertia mass coefficient of the flywheel 62, thereby amplifying the inertia mass of the vibration exciter, and reducing the vibration frequency of the vibration exciter. In other embodiments, the inertance chamber 6 can be mounted on the upper or lower surface of the inertial mass 3 in any position where the space allows and does not affect the movement of the inertial mass 3.
In some alternative embodiments, referring to fig. 6 and 7, the rotating shaft 61 may be rotatably connected to the inertial mass 3 through a bearing 63, that is, the rotating shaft 61 is directly installed on the inertial mass 3, a side surface of the inertial mass 3 may be provided with a circular hole with a certain depth, the bearing 63 may be accommodated in the circular hole, by providing the bearing 63, the initial friction of the rotating shaft 61 during rotation is small, and the flywheel 62 is fixedly installed at one end of the rotating shaft 61 close to the inertial mass 3, which is more beneficial to enable the rotational inertia generated by the flywheel 62 to act on the inertial mass 3; the inertia container 6 may further include a transmission member 64 installed at the other end of the rotation shaft 61, when the inertial mass 3 moves along the extending direction of the first spring 4 (i.e., moves up and down), the inertial mass 3 may drive the rotation shaft 61 to move up and down synchronously, and at the same time, the transmission member 64 drives the rotation shaft 61 to rotate around the axis of the rotation shaft 61, that is, the rotation shaft 61 drives the transmission member 64 to move during the up and down movement, and then the rotation member converts the up and down movement of the rotation shaft 61 into a rotational movement and drives the rotation shaft 61 to rotate around the axis thereof; in this embodiment, the transmission member 64 is arranged to drive the flywheel 62 to rotate in the process of up-and-down movement of the inertial mass block 3, power is provided from the inertial mass block 3, and no other driving device is required to be additionally arranged, so that resources and space are saved. The flywheel 62 may be welded to the rotating shaft 61, or may be fixed by a spline or other fixing member.
Further, referring to fig. 6 and 7, the transmission member 64 may include: the rack 641 may be fixedly disposed in the fixed box 1, wherein the rack 641 may be vertically and fixedly disposed in the fixed box 1, or may be obliquely disposed in the fixed box 1, in this embodiment, the rack 641 is vertically fixed near an inner edge of the fixed box 1; a gear 642 fixedly arranged on the rotating shaft 61, wherein the gear 642 is also fixedly connected with the rotating shaft 61 by welding or a spline or other fixing piece, the gear 642 is engaged with the rack 641, and the gear 642 is positioned at the side of the rack 641 and is engaged with the rack 641; when the rotating shaft 61 moves along the extending direction of the first spring 4, the rotating shaft 61 drives the gear 642 to move along the rack 641, and meanwhile, due to the meshing effect of the gear 642 and the rack 641, the gear 642 performs a rotating motion during the up-and-down movement, so that the gear 642 drives the rotating shaft 61 to rotate around the axis thereof. Of course, in other embodiments, the rotating shaft 61 may be driven to rotate through a transmission manner of a ball screw, and in this embodiment, the transmission configuration of the gear 642 and the rack 641 is implemented, so that the initial friction of the vibration exciter is from the rolling friction between the gear 642 and the rack 641, and the initial friction is smaller, and the initial damping of the vibration exciter can be greatly reduced compared with the scheme of ball screw transmission.
Preferably, as shown in fig. 6 and 7, the inertial container 6 may further include a limiting assembly 65, the limiting assembly 65 may include a connecting rod 651 and a limiting wheel 652, the connecting rod 651 connects the rotating shaft 61 and the limiting wheel 652, in this embodiment, the connecting rod 651 is sleeved at one end of the rotating shaft 61, the connecting rod 651 does not rotate along with the rotating shaft 61 during the rotation of the rotating shaft 61, the limiting wheel 652 and the gear 642 are respectively located at opposite sides of the rack 641, that is, the limiting wheel 652 is located at a back side of the rack 641 and is in rolling connection with the rack 641, during the up-and-down movement of the rotating shaft 61, the limiting wheel 652 rolls up and down along the rack 641 along with the rotating shaft 61, and by providing the limiting wheel 652, the limiting wheel 652 and the gear 642 are clamped at opposite sides of the rack 641, so that the rotating shaft 61 is prevented from being separated from the rack 641, the gear 642 cannot be perfectly engaged with the rack 641, and the limiting measure provided by the limiting wheel 652 can ensure that the inertial mass 3 has no instability problem during large-stroke movement.
In some embodiments, referring to fig. 6 and 7, the gear 642 is sleeved outside the rotating shaft 61 and can move along the axis of the rotating shaft 61, opposite sides of the gear 642 can be fixed by the fastening nuts 66, when the fastening nuts 66 on two sides clamp the gear 642, the gear 642 and the rotating shaft 61 are fixed together, the gear 642 and the rotating shaft 61 do not move relatively, the gear 642 can drive the rotating shaft 61 to rotate around the axis thereof during the rotation process and also drive the flywheel 62 to rotate, after the fastening nuts 66 on two sides are loosened, the gear 642 is sleeved outside the rotating shaft 61, the gear 642 and the rotating shaft 61 are not fixed, the gear 642 can rotate relative to the rotating shaft 61, the gear 642 can not drive the rotating shaft 61 to rotate during the rotation process, the flywheel 642 cannot be driven to rotate at this time, and the position of the gear 642 can be adjusted to be meshed with the rack 641 by loosening and tightening the fastening nuts 66 on two sides. In this embodiment, the fastening nuts 66 are disposed on two sides of the gear 642, so that whether the flywheel 62 rotates or not can be adjusted as required, and the frequency of the vibration exciter can be adjusted.
In some optional embodiments, referring to fig. 6 and 7, the inerter 6 may further include a limiting component 65, where the limiting component 65 limits the rotation shaft 61 from disengaging from the transmission member 64, in this embodiment, the limiting component 65 may be a slot structure that is clamped on the rotation shaft 61 and the transmission member 64, so as to prevent the rotation shaft 61 from disengaging from the transmission member 64, and the limiting component 65 may also be a structure similar to the connection rod 651 and the limiting wheel 652 described above; can realize that certain limiting effect is provided for the rotating shaft 61.
In some embodiments, referring to fig. 2, the fixed box 1 may further include a bottom plate 12, a lifting column 13 is fixed on the bottom plate 12, a top end of the lifting column 13 is connected to the top plate 11, and the lifting column 13 may adjust a height between the top plate 11 and the bottom plate 12; in the embodiment, the lifting column 13 of the fixed box 1 can realize the functions of up-down lifting and temporary locking, and when the vibration exciter needs to work, the lifting column 13 can be lifted to a certain height and temporarily locked; when the vibration exciter stops working, the lifting column 13 can descend and reset, the internal components can be stably placed in the fixed box 1, and compared with the conventional non-telescopic supporting column, the lifting column 13 is convenient to meet the height limit condition in actual transportation. And the lifting column 13 may be constructed in a hydraulic type or an electric type.
Preferably, the inertial mass 3 may have a plurality of sides, such as four sides, each side of the inertial mass 3 may be mounted with a plurality of inertias containers 6, each inertias container 6 includes a rotating shaft 61 connected to the inertial mass 3 and a flywheel 62 mounted on the rotating shaft 61, and the inertias containers 6 may further include a transmission member 64; when the rotating shaft 61 of the inertia container 6 is connected with the corresponding transmission piece 64, the inertia mass 3 can drive the flywheel 62 to rotate around the axis of the rotating shaft 61, that is, the inertia mass 3 can drive the flywheel 62 to rotate through the transmission piece 64 and the rotating shaft 61 in the process of moving up and down; when the rotating shaft 61 is disconnected from the corresponding transmission member 64, the inertial mass 3 cannot drive the flywheel 62 to rotate through the transmission member 64 in the process of moving up and down; by adjusting the connection state (i.e. disconnection or connection) of each rotating shaft 61 and the corresponding transmission member 64, the number of the flywheels 62 participating in the rotation can be adjusted, and the larger the number of the flywheels 62 participating in the rotation is, the larger the moment of inertia is, the lower the vibration frequency of the vibration exciter is, and thus the vibration frequency of the vibration exciter can be adjusted in stages. The vibration exciter can drive the inertia mass block 3 to have large amplitude by using the conventional stroke actuator 2, can adjust the vibration frequency of the vibration exciter by starting the inertia mass action in a grading manner, and realizes the vibration excitation of a long-span bridge structure by using a two-stage resonance principle.
Further, referring to fig. 6, the top plate 11 may be provided with a through hole, the actuator 2 includes a main body 21 located outside the top plate 11, and an expansion link 22 connected to the main body 21, the expansion link 22 penetrates through the through hole and extends to the inside of the fixed box 1, the through hole provided in the top plate 11 facilitates the expansion link 22 to pass through, the main body 21 is provided outside the fixed box 1, so that the space inside the fixed box 1 can be saved, and the top plate 11 can support the main body 21; the telescopic rod 22 may be fixedly provided with a flange plate 23, and the flange plate 23 is connected to the inertial mass 3 through the plurality of first springs 4; wherein, the center of flange plate 23 is equipped with a hole for can be fixed in the end of telescopic link 22 with flange plate 23 through the bolt, and flange plate 23 can be kept flat perpendicular to the axis of telescopic link 22, can make and be connected many first springs 4 between actuator 2 and the inertial mass block 3 through setting up flange plate 23.
In the embodiment, the self weight of the vibration exciter in a static balance equation is smaller, and the frequency of the vibration exciter can be reduced by the amplified inertia coefficient in a dynamic equation of the vibration exciter. When the inertial mass 3 of the vibration exciter is at rest, no force is applied between the gear 642 and the rack 641, and the tension spring (i.e., the spring) balances the deadweight of the inertial mass 3 and the flywheel 62, and the balance equation is as follows:
Figure 419762DEST_PATH_IMAGE006
，
in the above-mentioned formula,m 1 the mass of the inertial mass 3 and the mass of the flywheel 62 arem 2 The extension spring static force elongation is delta, wherein the extension spring static force elongation is the result of the combined action of the two sets of springs (the first spring 4 and the second spring 5) and the integral deformation, namely, the change distance of the position of the inertia mass block 3 from the spring without stress to the moment of bearing the total weight of the inertia mass block 3 and the flywheel 62,
Figure 617525DEST_PATH_IMAGE007
is the stiffness of the tension spring (i.e. the sum of the stiffness of all the first springs 4 and the second springs 5).
When the vibration exciter plays a role and the inertia mass block 3 moves up and down, the frequency of the vibration exciter is controlled by the rigidity of all the springs and the inertia mass coefficients of the inertia mass block 3 and the flywheel 62, and the equation is as follows:
Figure 37618DEST_PATH_IMAGE008
，
in the above two equations, there is the following relationship:
Figure 4437DEST_PATH_IMAGE009
，
in the above-mentioned formula,m 1 is the mass of the inertial mass 3,m e1 the mass of the flywheel 62 is the inertia coefficient of the inertia mass block 3m 2 The flywheel 62 has an inertia mass coefficient ofm e2 ，mThe apparent total mass of the inertial mass 3 and the flywheel 62,m e the mass coefficient of the total inertial mass is, fin order to be the frequency of the radio,αis the inertance magnification factor of the flywheel 62.
The single-stage gear 642 structure is adopted in the mechanical structure design for adjusting the frequency by the inertia effect, the initial friction of the transmission is small, and the inertia coefficient of the flywheel 62 in the single-stage gear 642 structurem e2 And mass of flywheel 62m 2 According to the law of conservation of energy, the translational energy of the flywheel 62 moving up and downE 1 Into rotational energy about an axis of rotation 61E 2 （E 1 = E 2 ) Then, there are:
translation energy of the flywheel 62:
Figure 369559DEST_PATH_IMAGE010
，
rotational energy of the flywheel 62:
Figure 54618DEST_PATH_IMAGE011
，
according toE 1 = E 2 Inertia coefficient of flywheel 62m e2 And the mass of flywheel 62m 2 The relationship of (c) is:
Figure 405965DEST_PATH_IMAGE012
，
in the above-mentioned formula,m 1 the mass of the mass which is the inertia,m e1 the mass of the flywheel 62 is the mass coefficient of inertiam 2 The inertia mass coefficient of the flywheel 62 ism e2 ，mThe apparent total mass of the inertial mass 3 and the flywheel 62,m e the total inertia mass coefficient is the static force elongation of the spring is delta,fin order to be the frequency of the radio,αis the inertance magnification factor of the flywheel 62,ωis the angular velocity of the gear 642 and the flywheel 62,Iin order to be the moment of inertia of the flywheel 62,ris the radius of the gear 642 and,Ris the flywheel 62 radius.
According to a frequency formula of a vibration exciter:
Figure 102657DEST_PATH_IMAGE013
it can be seen that the frequency is not only related to the magnitude of the inertial mass, but also positively related to the stiffness of the spring. The spring of the invention adopts the tension spring, when the number of turns of the spring is reduced, the rigidity of the spring is increased, and the frequency of the vibration exciter can be adjusted upwards.
The rotation of the flywheel 62 thus acts to increase the effect of inertia, which can significantly reduce the frequency of the exciter and significantly increase the amplitude of displacement of the beam 7 in the intended mode of excitation. And the vibration frequency of the vibration exciter can be regulated in a grading way by adjusting the starting inertia mass action of the flywheels 62 with different quantities and the number of turns of the tension spring so as to be suitable for different practical projects.
The vibration exciter provided by the embodiment of the invention has the following advantages:
1) The advantage of two-stage resonance over one-stage resonance is: the inertia mass block 3 of the vibration exciter can generate large amplitude by the actuator 2 with the conventional stroke, the limitation of the stroke of the actuator 2 is small, the appearance size and the cost of the vibration exciter are reduced, and the mechanical property of the vibration exciter is improved.
2) The tension spring is used for providing rigidity, the limiting wheel 652 is used for providing a limiting measure, and the mass block does not have the instability problem when moving in a large stroke.
3) The inertance effect is realized by the transmission structure of the gear 642 and the rack 641, the initial friction of the system is from the rolling friction of the gear 642 and the rack 641 and the rotation friction of the bearing 63, the initial friction is smaller, and the initial damping of the system can be greatly reduced compared with the scheme of ball screw transmission.
4) The frequency of the vibration exciter is adjusted in a grading mode through the inertia effect, when the inertia container 6 is added, the flywheel 62 is driven to rotate through the gear 642 and the rack 641 along with the up-and-down movement of the inertia mass block 3, the inertia coefficient generated by the flywheel 62 is amplified, and the system frequency can be adjusted downwards. Otherwise, the system frequency is adjusted up.
5) The frequency of the vibration exciter can be adjusted by adjusting the number of turns of the tension spring. When the number of turns of the tension spring is reduced, the rigidity of the tension spring is increased, and the system frequency can be adjusted upwards. Otherwise, the system frequency is adjusted downwards.
In the description of the present invention, it should be noted that the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are merely for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "coupled" are to be construed broadly and encompass, for example, both fixed and removable coupling as well as integral coupling; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
It is to be noted that, in the present invention, relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a … …" does not exclude the presence of another identical element in a process, method, article, or apparatus that comprises the element.
The foregoing are merely exemplary embodiments of the present invention, which enable those skilled in the art to understand or practice the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A bridge vibration exciter is used for testing the damping ratio of a bridge, and is characterized by comprising:
the fixing box (1), the fixing box (1) comprises a top plate (11), and the top plate (11) is provided with an actuator (2);
an inertial mass (3) located in the fixed box (1), the inertial mass (3) being connected to the actuator (2) by a first spring (4), and the inertial mass (3) being connected to the top plate (11) by a second spring (5), the second spring (5) being configured to bear the weight of the inertial mass (3);
the actuator (2) is used as an excitation source, the first spring (4) is connected with the inertial mass block (3) and excites the inertial mass block (3) to achieve a resonant state of the inertial mass block (3) and the actuator (2), the resonant state is a first-stage resonance, and in the first-stage resonance, the amplitude of the inertial mass block (3) is amplified;
the amplitude of the inertia mass block (3) is n times of the amplitude of the actuator (2), wherein n is a first-stage resonance amplification coefficient, n is greater than 1, and n is related to the rigidity ratio of the first spring (4) and the second spring (5), and the first-stage resonance amplification coefficient n is adjusted by adjusting the number of turns of the first spring (4) or the second spring (5).
2. The bridge exciter of claim 1, wherein:
an inertial container (6) is mounted on the side surface of the inertial mass block (3), and the inertial container (6) comprises a rotating shaft (61) connected with the inertial mass block (3) and a flywheel (62) mounted on the rotating shaft (61);
when the inertia mass block (3) moves along the extending direction of the first spring (4), the inertia mass block (3) drives the flywheel (62) to rotate around the axis of the rotating shaft (61).
3. The bridge exciter of claim 2, wherein:
the rotating shaft (61) is rotatably connected to the inertial mass (3) through a bearing (63), and the flywheel (62) is fixedly arranged at one end, close to the inertial mass (3), of the rotating shaft (61);
the inerter (6) further comprises a transmission piece (64) installed at the other end of the rotating shaft (61), when the inertial mass block (3) moves along the extending direction of the first spring (4), the inertial mass block (3) drives the rotating shaft (61) to move synchronously, and meanwhile, the transmission piece (64) drives the rotating shaft (61) to rotate around the axis of the rotating shaft (61).
4. A bridge exciter according to claim 3, wherein the transmission member (64) comprises:
a rack (641) fixed to the fixed box (1);
and the gear (642) is fixedly arranged on the rotating shaft (61), the gear (642) is meshed with the rack (641), when the rotating shaft (61) moves along the extending direction of the first spring (4), the rotating shaft (61) drives the gear (642) to move along the rack (641), and meanwhile, the gear (642) drives the rotating shaft (61) to rotate.
5. The bridge exciter of claim 4, wherein:
be used to container (6) still includes spacing subassembly (65), spacing subassembly (65) include connecting rod (651) and spacing wheel (652), connecting rod (651) are connected axis of rotation (61) with spacing wheel (652), spacing wheel (652) with gear (642) are located the relative both sides of rack (641).
6. The bridge exciter of claim 4, the method is characterized in that:
the two opposite sides of the gear (642) are fixed through fastening nuts (66), and whether the gear (642) is meshed with the rack (641) is adjusted by loosening and tightening the fastening nuts (66) on the two sides.
7. The bridge exciter of claim 3, wherein:
the inerter (6) further comprises a limiting component (65), and the limiting component (65) limits the rotating shaft (61) to be separated from the transmission piece (64).
8. The bridge exciter of claim 1, wherein:
the fixed box (1) further comprises a bottom plate (12), a lifting column (13) is fixedly arranged on the bottom plate (12), the top end of the lifting column (13) is connected with the top plate (11), and the lifting column (13) adjusts the height between the top plate (11) and the bottom plate (12).
9. The bridge exciter of claim 1, wherein:
a plurality of inertial containers (6) are mounted on the side surface of the inertial mass block (3), each inertial container (6) comprises a rotating shaft (61) connected with the inertial mass block (3) and a flywheel (62) mounted on the rotating shaft (61), and each inertial container (6) further comprises a transmission piece (64);
when the rotating shaft (61) of the inertial container (6) is connected with the corresponding transmission piece (64), the inertial mass block (3) drives the flywheel (62) to rotate around the axis of the rotating shaft (61); the number of the flywheels (62) participating in rotation is adjusted by adjusting the connection state of the rotating shafts (61) and the corresponding transmission pieces (64).
10. The bridge exciter of claim 1, wherein:
the top plate (11) is provided with a through hole, the actuator (2) comprises a main machine (21) positioned on the outer side of the top plate (11) and an expansion rod (22) connected with the main machine (21), and the expansion rod (22) penetrates through the through hole and extends to the inside of the fixed box (1);
the telescopic rod (22) is fixedly provided with a flange plate (23), and the flange plate (23) is connected with the inertia mass block (3) through a plurality of first springs (4).
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